1. Field of the Invention
The present invention relates to a system for recycling a high-boiling-point waste photoresist stripper, and more particularly, to a system and method for recycling a high-boiling-point waste photoresist stripper, wherein an expensive high-boiling-point stripper solvent may be easily recycled at high yield and in the level of high-purity electronic grade from a high-boiling-point waste photoresist stripper generated in a process of manufacturing a liquid crystal display or a semiconductor device.
2. Description of the Related Art
With the drastic advancement of information communication industries, the demand for electronic devices and liquid crystal displays (LCDs) using a variety of semiconductor devices is continuously increasing. Accordingly, a photoresist, which is a key to the formation of a micropattern of a wafer and a circuit board, and an expensive stripper for dilution and removal of such a photoresist are increasingly required, and furthermore, the need for recycling such a stripper used is on the rise.
For example, a waste stripper is mainly generated during a photo process for forming a circuit pattern in the course of manufacturing electronic parts such as semiconductor wafers, LCDs, glass substrates, etc., and the waste stripper contains not only stripper solvents but also a photoresist resin, water, impurities such as heavy metals, etc.
The waste stripper is mostly removed by way of incineration or landfill after simple pre-treatment, but may cause environmental problems and treatment cost problems from generation of the waste to removal thereof. Ultimately, competitiveness of IT industries may become weakened and thus ensuring resources through recycling of waste solvents is urgently required.
As electronic parts and devices combined with IT technology have been rapidly developed, kinds or functions of thinner and stripper used in the manufacturing processes have become diversified. Nevertheless, the amounts of main stripper solvents which are reused through recovery and purification after having been used for processes of manufacturing electronic parts such as TET-LCD (which is an ultrathin film liquid crystal display), etc. are very small at the present time.
Particularly in TET-LCD fields, substrates are large-sized and panel prices are falling, and thus the demand for processing cost savings is increasing. Under circumstances in which high prices of raw materials of thinners and strippers result from the recent rise in oil prices, cost competitiveness has to be ensured. Hence, when waste strippers are utilized again as raw materials through purification, the use of raw materials is reduced, and also, environmental problems which become more serious and treatment cost problems may be solved.
Extensive research to recycling techniques of the waste in a stripping process is ongoing these days in terms of economy, environment and efficiency. In regard to a waste stripper recycling technique, Korean Patent No. 0901001 and Japanese Patent Application Publication No. 2005-288329 disclose a technique for recycling a stripper solvent by removing a low-boiling-point material such as water, etc. and a high-boiling-point material such as a photoresist resin, etc., from the waste stripper, and Korean Patent No. 0899777 discloses a high-yield recycling method in which the recycling loss is minimized.
However, due to the recent advancement of LCD and semiconductor industries, a new type photoresist resin is being used depending on the development of a novel memory semiconductor, and a highly functional stripper organic solvent is required to easily dissolve the photoresist resin in the course of stripping the photoresist resin during the manufacturing process. Although the use of high-boiling-point stripper solvents having high stripper solubility is increasing, limitations are imposed on recycling the high-boiling-point stripper solvents using the recycling method as above.
In the recycling method as above, because of high-boiling-point properties, including high viscosity, thermal decomposition and color change, the high-boiling-point stripper organic solvents are difficult to separate and purify from heavy photoresist resin and metal components, and are allowed to excessively remain in order to prevent generation of processing difficulties, and then discarded together with high-boiling-point impurities.
Also, the recovery efficiency of high-boiling-point stripper organic solvents recovered by the conventional recycling methods approximates to 15%, which is regarded as economically insignificant. The quality including purity and color of the recovered high-boiling-point stripper solvents is poor and thus the recycling value thereof is low, which is undesirable.
The demand for techniques for recycling and recovering of expensive high-boiling-point stripper organic solvents is being agitated in the related industries, but there are still no alternatives to the recycling techniques at home and abroad.
Hence, there is an urgent need to secure advanced recycling techniques able to recover expensive high-boiling-point stripper organic solvents through recycling and purification from a photoresist residue which is being discarded, in addition to the typical stripper organic solvent of the waste photoresist stripper. If a high-boiling-point stripper solvent which is an expensive valuable resource completely imported from abroad is recovered in a large amount at high recovery efficiency and then reused, efficient energy management and competitiveness of IT related companies are likely to remarkably increase, and more practical environmental improvement effects are expected.